Tomás Porras Naranjo

Low-inertia power systems require scenario-dependent assessment of additional frequency support. This study develops a computational-intelligence-based framework for minimizing missing virtual inertia with conventional inertia fixed as an external input. Following a five-metaheuristic comparison, a whale optimization algorithm (WOA)-based search is coupled to real-time electrical simulation on RTDS NovaCor Light through RSCAD FX. Acquired trajectories determine candidate feasibility under event-direction rate of change of frequency (RoCoF), nadir, and zenith limits. A 70-case experiment combines conventional inertia of 1.0–4.0 s with signed demand changes of 5–25 MW. Of these cases, 56 yielded feasible outputs: 24 required no addition and 32 required 0.155–7.349 s on the system base. The remaining 14 cases at ±25 MW had no feasible candidate within the tested 0–10 s additional-inertia interval and budget. For positive-support cases, the nearest constraint shifted from RoCoF at 10–15 MW to nadir or zenith at 20 MW, revealing the need to assess frequency extrema and both disturbance directions. Their median optimization time was 28.95 min, supporting prospective scenario assessment. Virtual support was represented by an ideal equivalent generator-inertia increment; consequently, the best-found outputs inform battery energy storage and virtual synchronous machine design without demonstrating physical converter delivery.

Multimodal electric transport systems demand substantial active and reactive energy, making power-quality management essential for ensuring efficient and reliable operation. This paper analyses reactive-energy transport in mass-transit networks and introduces a unified current-based framework that enables a consistent interpretation of the conventional power factor under harmonic distortion, fundamental unbalance, and short-term load fluctuation, without modifying its original definition. The framework enables a consistent assessment of compensation needs, independent of billing schemes, and is aligned with the way modern compensation equipment is specified and controlled. Applied to the Metro de Medellín system, field measurements and digital simulations show that traditional reactive-energy limits fail to distinguish between harmful and beneficial operating conditions, leading to disproportionate charges under the former Colombian regulation. Beyond this case, the proposed framework is directly applicable to other electric-mobility systems—including railways, trams, trolleybuses, and electric-bus networks—providing clearer technical signals for compensation planning and offering a comprehensive basis for future regulatory approaches that integrate multiple power-quality phenomena.